A series of unusual abortions occurred in Thoroughbred and Quarterhorse mares in the Hunter Valley region of New South Wales from mid-March to November 2004. The initial link between early cases was the microbiological culture of atypical environmental coryneforms from the stomach contents and/or lungs of fetuses aborted on different properties.Methods
The unique pathologic lesions were described with a case definition and the term ‘equine amnionitis and fetal loss’ (EAFL) was established.Results
The causal factor was the ingestion of the processionary caterpillar (Ochrogaster lunifer). Bacteria from the Actinomycetales order were isolated from 40% of the combined suspect and confirmed EAFL cases and included Microbacterium arborescens, Cellulomonas sp., Arthrobacter spp. and Cellulosimicrobium sp. Other bacteria isolated included various Gram-negative bacilli and Gram-positive cocci.Conclusions
Although the predominant type of bacteria isolated from EAFL was environmental coryneforms, it is important to note that a variety of bacteria were associated with the characteristic histopathological changes outlined by the case definition. This highlights the importance of histopathology on both fetal membranes and fetuses, as well as culture to confirm EAFL and to exclude other possible causes of abortion.